Sometimes reinstalling is the quickest way to solve a problem, for example if an upgrade failed or if your graphics driver is broken. When reinstalling, you're most likely want to preserve two things:

/home folder with your files and settings

Entries in boot menu (if you have multiple OS installed)

How To Reinstall Ubuntu

Since Hardy it is possible to reinstall Ubuntu without losing the content of the /home folder (the folder that contains program settings, internet bookmarks, emails and all your documents, music, videos and other user files). This can be done even if /home is not on a separate partition (which is the case by default if you did not manually separate it when installing Ubuntu originally). This tutorial can also be used to upgrade Ubuntu (eg 11.04 -> 12.04 from a 12.04 live-CD).

Before doing anything

This operation should not damage your documents but, for security, backup your documents and settings (including /home hidden files) on external disk or DVDs. (eg via CloneZilla) Note: Some special applications settings may be in system folders, eg LAMP, see below in the thread.

Run the Ubuntu installer

Choose the right option

There are two possibilities - choose the one that fits what the installer is showing:

- If an "Upgrade 1X.XX to 1Y.YY" option is available (like in the screenshot below), choose it.

- Or, if the above option is not available, choose manual partitioning ("Something-else" option), then select Ubuntu system partition, set its mount point as "/". Be sure to keep the same format type, the same size, and untick the "Format" checkbox or all data on "/" will be deleted!. Also set other partitions (/boot, /home... see DiskSpace) if needed.

Then finish the installation process. (this may take several hours, like a normal install)

After reinstalling

After reinstalling, user accounts must be re-created with the same login and password.